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41.
A kind of microstructured polymer optical fiber with elliptical core has been fabricated by adopting in- situ chemical polymerization technology and the secondary sleeving draw-stretching technique.Microscope photography demonstrates the clear hole-structure retained in the fiber.Though the holes distortion is visible,initial laser experiment indicates that light can be strongly confined in the elliptical core region, and the mode field is split obviously and presents the multi-mode characteristic.Numerical modeling is carried out for the real fiber with the measured parameters,including the external diameter of 150μm,the average holes diameter of 3.3μm,and the average hole spacing of 6.3μm by using full-vector plane wave method.The guided mode fields of the numerical simulation are consistent with the experiment result. This fiber shows the strong multi-mode and weak birefringence in the visible and near-infrared band,and has possibility for achieving the fiber mode convertors,mode selective couplers and so on. 相似文献
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纳米半球微镜阵列结构对GaN基LED光提取效率的影响 总被引:1,自引:0,他引:1
为了分析表面纳米半球微镜结构对GaN基发光二极管(LED)光提取效率的影响,利用时域有限差分法(FDTD)分别对GaN、ZnO、SiO2、聚苯乙烯组成的半球微镜结构进行了分析和比较,同时用模式分析方法从理论上对FDTD计算结果进行了进一步验证。研究发现,在亚波长范围,折射率较小的材料不利于导模与表面结构层的耦合,不会对光提取效率的提高产生明显影响。相比之下,折射率较大的材料会使更多的模式耦合到半球微镜阵列层,更有利于光提取效率的提高;当材料选定,纳米半球半径增加时,光提取效率也逐渐增加,优化后半径为600 nm的半球微镜阵列结构GaN基LED,其光提取效率比没有结构的普通平板LED增强5.66倍,在以上波导材料结构中最为优化。在此基础上,通过等效折射率的计算得到半球微镜结构的等效折射率模型,并利用非对称平板模式分析的办法对以上得到的结论进行了分析和验证。这些结果对实际的高性能GaN基LED的设计与优化具有重要意义。 相似文献
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Hot-carrier degradation for 90nm gate length LDD-NMOSFET with ultra-thin gate oxide under low gate voltage stress 下载免费PDF全文
The hot-carrier degradation for 90~nm gate length lightly-doped drain
(LDD) NMOSFET with ultra-thin (1.4~nm) gate oxide under the low gate
voltage (LGV) (at Vg=Vth, where Vth is the
threshold voltage) stress has been investigated. It is found that the
drain current decreases and the threshold voltage increases after the
LGV (Vg=Vth stress. The results are opposite to the
degradation phenomena of conventional NMOSFET for the case of this
stress. By analysing the gate-induced drain leakage (GIDL) current
before and after stresses, it is confirmed that under the LGV stress
in ultra-short gate LDD-NMOSFET with ultra-thin gate oxide, the hot
holes are trapped at interface in the LDD region and cannot shorten
the channel to mask the influence of interface states as those in
conventional
NMOSFET do, which leads to the different degradation phenomena from those of the
conventional NMOS devices. This paper also discusses the degradation in the
90~nm gate length LDD-NMOSFET with 1.4~nm gate oxide under the LGV stress at
Vg=Vth with various drain biases. Experimental results show that
the degradation slopes (n) range from 0.21 to 0.41. The value of
n is
less than that of conventional MOSFET (0.5-0.6) and also that of the long gate
length LDD MOSFET (\sim0.8). 相似文献
48.
本文主要回顾了电磁场的对偶性和电荷量子化解释,并把电磁场的对偶性推广到了一般线性介质状况,讨论了磁单极及其整体规范变换,并给出了Dirac磁单极产生的磁矢势的普遍表达式;最后给出了Maxwell方程的U(1)对称性及其对偶性的费米子描述方法。 相似文献
49.
简要介绍了非对易三维空间的性质,并在非对易三维空间中讨论谐振子体系.得出谐振子体系中空间和动量算符的特有形式,以及给出三维非对易谐振子体系的哈密顿量的明显表达式. 相似文献
50.
A specially designed experiment is performed for investigating gate-induced
drain leakage (GIDL) current in 90nm CMOS technology using lightly-doped
drain (LDD) NMOSFET. This paper shows that the drain bias $V_{\rm D}$ has a
strong effect on GIDL current as compared with the gate bias $V_{\rm G}$ at the
same drain--gate voltage $V_{\rm DG}$. It is found that the difference between
$I_{\rm D}$ in the off-state $I_{\rm D}-V_{\rm G}$ characteristics and the
corresponding one in the off-state $I_{\rm D}-V_{\rm D}$ characteristics, which is
defined as $I_{\rm DIFF}$, versus $V_{\rm DG}$ shows a peak. The difference between
the influences of $V_{\rm D}$ and $V_{\rm G}$ on GIDL current is shown
quantitatively by $I_{\rm DIFF}$, especially in 90nm scale. The difference is
due to different hole tunnellings. Furthermore, the maximum $I_{\rm DIFF
}$($I_{\rm DIFF,MAX})$ varies linearly with $V_{\rm DG}$ in logarithmic coordinates
and also $V_{\rm DG}$ at $I_{\rm DIFF,MAX}$ with $V_{\rm F}$ which is the characteristic
voltage of $I_{\rm DIFF}$. The relations are studied and some related
expressions are given. 相似文献